Enhancing hydraulic risk assessment using next-generation satellite remote sensing: the RESCUE_SAT project

The frequency of occurrence and the severity of floods are increasing as a consequence of climate change. It affects ecosystems health, human activities, infrastructure safety and durability. Adaptation strategies to climate changes are oriented to the mitigation of the consequences of these events. Hydraulic and hydrological forecasting through numerical simulation is the primary and challenging decision support tool for implementing prevention and protection policies. The numerical algorithms are based on Digital Terrain Models (DTM) for elevation (DEM) and for land cover. The resolution of DTM depends on the technological equipment used for surveying. Typically, hydrological models for the simulation of rainfall-runoff process use terrain data at a lower resolution (101m) if compared to hydraulic models that simulate the flood propagation and need much finer spatial resolution (100 m). The RESCUE_SAT project (Agreement n. 2025-2-HB.0), supported by the Italian Space Agency (ASI) under the "Innovation for Downstream Preparation for Science"(I4DP_SCIENCE) program, integrates advanced hydrological and hydraulic modelling with multi-scale satellite Earth Observation (EO) imagery. The overall objective of the project is to enhance the flood forecasting by the integration of detailed EO data into the rainfall runoff simulation, in order to simulate, in a unique platform, hydrological large-scale phenomena and hydraulic local processes, as flow around obstacles such as bridge piers or embankments. To this end, the project will process SAR and multispectral and hyperspectral optical satellite data to generate up-To-date and continuously updated information. While multispectral Sentinel-2 imagery and hyperspectral data from the PRISMA mission will be used to generate improved land cover maps, SAR data from the COSMO-SkyMed constellation will be used to generate high-resolution DEM. The achieved DEM is expected to improve significantly the model's performance, enhancing the accuracy and enabling the best identification of risk areas, in particular locally at the interferences between natural flow and infrastructure. By combining the computational efficiency of DEM based calculations with advanced hydrological and hydraulic modelling, the project aims to generate physically based flood maps optimizing cost and time efficiency. In addition, the project can easily fuse ground-based data from laser scanning and UAV surveys, equipped with different payloads, in areas where infrastructure interacts with surface hydraulic systems, allowing for the consideration of local effects. In conclusion, the RESCUE_SAT project aims to demonstrate the benefits of integrating and fusing multi-source satellite data into flood risk assessment frameworks for medium to large scale areas. It can be really promising for evaluating local and subscale phenomena in flood hazard and severity mitigation, paving the way for improved monitoring, assessment, and prevention of hydraulic risk, especially those affecting critical infrastructure.